Effective use of water resources has recently been in demand due to industrial developments and population growth. In order to meet the demand, reuse of wastewater such as industrial wastewater is important. In order to reuse such wastewater, water purification, i.e. separation of other substances from the water, is necessary. As a method for separating other substances from the water, various methods such as membrane separation, centrifugal separation, activated carbon adsorption, ozone treatment, and floating substance removal by aggregation have been known. The methods are capable of removing substances which are contained in water and can exert considerable influence on environment, such as phosphorus and nitrogen, and removing oil and clays dispersed into the water.
Among the methods, the membrane separation is one of the methods which are most generally employed for removing insoluble substances in water, and a filter aid is used in the membrane separation from the viewpoints of membrane protection and an increase in flow rate of water which contains hardly-dewaterable substances.
Meanwhile, as a method for removing harmful substances and valuable substances from water, a method including causing a predetermined reaction of a substance dissolved in water so that the substance is precipitated as a precipitate and separating the precipitate from the water has been known. For example, there has been known a method including precipitating copper ions in water, aggregating precipitated copper particles by adding a polymer having aggregation function in order to prevent discharge of the precipitated fine copper particles to other systems, and separating and recovering copper as aggregates.
However, since the aggregates per se include a large amount of the polymer in the above-mentioned method, the method has a problem of low copper recovery efficiency and low copper purity per unit volume of the aggregates. Further, a problem of a large waste amount is detected with the method since a large amount of sludge which should finally be disposed remains after the separation of copper from the aggregates.
A copper recovery apparatus which is capable of: reducing a waste amount, realizing fine copper particles precipitated in water directly to solid-liquid separation, and enhancing copper recovery efficiency is in need.